Machine for making articles, such as display covers from thin plastic sheet material



C. E. MAYNARD ETAL MACHINE FOR MAKING ARTICLES, SUCH AS DISPLAY COVERS Sept. 5, 1950 7 FROM THIN PLASTIC SHEET MATERIAL Filed Dec. 13, 1946 6 Sheets-Sheet 1 D TM S W H I u W MW r T llll ill tlllllI r l l l l I l l l l 6.. I... |l|| a I a w M W 2m Hnuwhunl l hln H J w S3 N3 .fr NR r A NW MN IHH MN 0 2 b r M N Sept. 5, 1950 E. MAYNARD ETAL MACHINE FOR MAKING ARTICLES, sucH AS DISPLAY COVERS FROM THIN PLASTIC SHEET MATERIAL H6 Sheets-Sheet 22 Filed Dec. 13, 1946 4 m n T M W P mar Cunzafi'n AMDBYZL'WISJII- Gear/arson I 9 ATTOR EYS Sept. 5, 1950 c. E. MAYNARD ETAL 2,521,387

MACHINE FOR MAKING ARTICLES, sucH AS DISPLAY COVERS FROM THINPLASTIC SHEET MATERIAL 6 Sheets-Sheet 3 Filed Dec; 13, 1946 INVENTORS ATTO N EYS C. E. MAYNARD EI'AL MACHINE FOR MAKING ARTICLES, SUCH AS DISPLAY COVERS .FROM PLASTIC SHEET MATERIAL 9 l 0 w w 1 5. D m. M i a F Sept. 5, 1950- c. E. MAYNARD ETAL 2,521,387

momma FOR MAKING ARTICLES, sucn AS DISPLAY- COVERS I FROM THIN PLASTIC SHEET MATERIAL Filed-Dec; 15, .1946- 6 Sheets-Sheet 5 INVENTORS C/M u'sib Air/747110170 Alva EH76 .Guamraa ATTO NEYS MACHINE FOR mine ARTICLES, sucn AS DISPLAY COVERS FROM THIN PLASTIC SHEET MATERIAL P 11950 c E. MAYNARD EIAL 2,521,387

Filed Dec; 13, 1945 e Sheets-Sheet s ATTO EYS Patented Sept. 5, 1950 MACHINE FOR MAKING ARTICLES, SUCH AS DISPLAY COVERS FROM THIN PLASTIC SHEET MATERIAL Charles Edgar Maynard, Florence, and Lewis H.

'Gustafson, Northampton, Mass, assignors, by mesne assignments, to Design Center, Ina, Flushing, N. Y., a corporation of New York Application December 13, 1946, Serial No. 716,014

6 Claims. I

This invention relates to improvements in machines to make hoods or similar articles of ornamental plastic material. The hoods are made in commercial practice under this invention from transparent material and are used in making up display packages 'for retail selling of other things. For example, a display package consists of a bottom tray, a hair brush on the tray, and a transparent hood to cover the hair brush. The practice is to sell the "brush with its display package as one unit. In this use the hood is in the form of .a hollow pl'asticfshe'll with a bottom opening adapted to receive and the hood cavity deep enough to contain the hair brush, and the tray closes the bottom opening. The hood as made under this invention has the si'g nificant features of being a thin one piece seamless shell of entirely self-sustaining form, of having a curved tapered surface, of being of highly ornamental plastic material which maybe and preferably is highly transparent.

'It is well known in the plastics industry, as its hand book and commercial literature shows, that with the ingredients of a plastic mix, a fine ornamental quality of plastic material can be made up in sheet form. The high quality desired from the material for ornamental purposes can be attained much easier and at much lower cost in sheet than in molded 'form. For this reason it is desirable in making ornamental plastic hoods to make them from sheet plastic material provided the quality of the sheet can be retained in shaping it to the desired hood form. This is also desirable ii the hoods can be made from sheet plastic material at a 'cost way below the cost of molding them.

So far as we were informed prior to this invention it was not practical to draw ornamental sheet plastic material to a depth beyond about one half of the diameter or width of the finished piece. The article would "not draw to a good appearance under prior practice. .The commercial "piece we firsthwanted to draw, rather than mold, was about two and a halt inches wide by nine and a quarter inches long andtwo andone half inches deep. That is, "the depth was about equal to the width. This put the dimensions very substantially outside the accepted limits of the art in drawing thin sheet plastic material as of the :time we began to work to conceive our improvements. 'Tlietni'ckness of the sheet plase tic material we wanted to draw as a transparent hood to cover the hair brush in the "ipa'cfkage mentioned above was about ten thousandths of an inch. The sheetswere available from several large plastic manufacturers and with exceptionally fine transparent and ornamental quality in the flat form. On enquiry about the feasibility of drawing these sheets to the form we wanted we were advised that it could not be drawn according to the art knowledge as of thatptime This is the background of the problem met'by our invention herein disclosed. In working out this problem however it will be seen that we have improved the .art of drawing hoods generally within the range of drawing depths heretofore considered practical but more particularly and more important we have extended the depth range far beyond what was before considered feasible in drawing the sheet plastic material while retaining in the deep hood vform the fine appearance of the sheet form of ornamental plastic material.

The invention will be considered first with regard to drawing the sheet material to hood form of useful depths, that is for articles of hood form generally, and then for articles of hood form V drawn deeper than before considered practical.

The invention is in the machine disclosed.

The disclosure of the machine will also disclose the method and the invention will be pointed out in the claims.

Referring to the drawings:

Fig. l is a side View of the machine;

Fig. 2 is a View looking from the right end "of Fig. 1;

Fig. .3 is a view looking from the opposite :side of Fig. l of parts on that side to distinguish from parts seen in the upper left hand :portion :of the View in Fig. 1'; I

Fig. 4 is :a fragmentaryplan detail of parts indicated in Fig. '1; r

Fig. 5 is a view of the machine with some parts broken away and some in section to indicate the relative position of tools during the hood shaping step;

Fig. 6 is a detail view indicating part of th mechanism for cutting off a portion of the sheet plastic material for the shaping tools of Figfb;

Fig. '7 is a detail illustrating the action of a clamping plate and its holding mechanism with relation to other tools;

Fig. 8 is a detail of the mechanism of Fig. 'l with parts in different positions;

Fig. 9 is a fragmentary oblique drawing of the heater plates, .feed jaw means and a lower knife mechanism;

Fig. 10 is an enlarged fragmentary section of feed jaws in position to grasp the web;

Fig. 11 shows the parts in Fig. in different position;

Fig. 12 is a view of the hood shaped from the fiat sheet material, but before trimming;

Fig. 12A is a view of a hood much longer than it is wide and of a drawn depth about equal to its width, to indicate a'transparent hood made from sheet plastic material of about ten thousandths inch thickness;

Fig. 13 is a somewhat diagrammatic view of the machine indicating the operation of applying air blasts to free the hood from its shaping tool and blow it to one side to a receiving bin before starting another cycle of operations;

Fig. 14 is a diagrammatic view to disclose, with its discussion, a way for arranging power operable control means for the sequence of operations in each machine cycle and for full automatic operation of the machine; and

Fig. is a diagram to indicate a heating plan for parts of the machine.

The idea for the main part of the machine will first be described, with particular reference to Figs. 1, 2 and 5. It consists of mechanism for reciprocating a male forcing die toward, into and then away from the aperture of a draw plate. Heated sheets of plastic material are periodically clamped in timed relation with the reciprocation of the die to the surface of the draw plate surrounding its aperture. The portion of the sheet inside the area of the portion directly clamped, is drawn to shape in conformity with that portion of the male die which is adapted to pass into and protrude through the draw plate aperture during reciprocation. The shaped hood is designated by the letter is and is shown in Fig. 12. Its marginal portion, that which has been clamped to the draw plate, is indicated at Z.

In Figs. 1, 2 and 5, a stand I bears a frame consisting of a base plate 2 and a top plate 3 supported from the base plate 2 by supporting posts 4 and fixed thereto by nuts 5. A cylinder 5 mounted on the top plate 3 slidably carries a piston 'I to which is fixed a piston rod 8. The rod 8 may slide freely in a bore in the top plate 3 when so urged by the action of fluid pressure on the piston I, and is attached to a cylinder plate 9 by means of an adapter I0. A die plate II is fixed to plate 9 and carries two brackets I2 to which are pivoted at I3 latching members I4. The latches I4 support a clamping plate I5 during a part of the work stroke, and through other mechanism now to be described and illustrated in Figs. 2, 7 and 8 function to release the clamping plate I5 to clamping position during the remainder of the work stroke. Pivotally mounted on the latches Id at It are pawls I! which cooperate with tripping elements I8 to rotate the latches I4 around pivots I3 to release clamping plate I5 when the plates 9 and II are being driven by the piston i in the direction indicated in Fig. '7, and which swing around pivots E5 to clear the tripping members I8 without disturbing latches I4 when plates 9 and I i are moving as in Fig. 8. The tripping members 8 are fixed to straps I9 which are fastened to the frame supporting posts 4, as by screws.

A die depends from the plate I I, fixed thereto, as by screws 2|, Fig. 5, and is formed to the shape of the hood cavity to be produced, being deeper for the hood of Fig. 12A than for the hood of Fig. 12. The clamping plate I5 lies below the plate II, spaced therefrom by spacers 23, and is held to the. plate II by the latching members I l. The clamping plate I5 slides on, and is guided by, spring holding rods 24 when released by the latching members I4, and drops o-nto cushioning springs 25, which are supported on the rods 25 by nuts 25. Lock nuts 21 prevent the nuts 25 from jarring free of the threaded portion of the rods 24. The rods 24 are fixed to the plate II at 28 and extend through bores 29 in the plate I5, Fig. 2. The clamping plate I5 has an opening 35 machined therein to permit the die 20 to extend from the plate II through the plate I5 when said plate is held in its uppermost position by the latching members 14.

Beneath the plunger assembly, and positioned in cooperating relationship therewith, a draw plate 3| is borne by supports 32 which are fixed to the base plate 2. The draw plate 3i is fixed to the supports 32 as by bolts 33 and has a machined aperture 34 to receive the die 20 and a heated sheet of plastic material which is drawn to an overlying position on the draw plate 3| by feeding means to be described later.

Extending rearwardly from the top plate 3 and as viewed from the left of Fig. 1, left and right brackets 35 and 35 of web feed mechanism are attached to plate 3 by screws 31 and support a reel of flexible sheet plastic material 38, and feed rolls 39 and 48 (Fig. 3). The reel 38 is borne by shaft 4| which is rotatably mounted on rollers 42 of an anti-friction reel mounting 43. A suitable braking device may be used to frictionally restrain the reel 38 against overfeeding after the feed rolls 39 and 49 have come to rest. Such a device could have many forms, for example, that indicated by number 44 in Fig. 3 in which a collar 45 pinned to the shaft 4| is held between a hinged brake shoe 46 and a slidable shoe 41. Pressure is exerted on the collar 45 by the hinged shoe 46 through a wing nut 58 and by the slidable shoe 4! through a thumb LI-I screw 49.

The feed rolls 39 and MI, Fig. 3, are driven, through suitable gearing to be described later, by a rack 59 slidable in a slotted rack guide 5| mounted on bracket 52 which is fixed to, and therefore reciprocates with, the cylinder plate 9. The rack slot in guide 5| extends from a lower stop 54 to a cap 55 secured to the rack guide 5|. A screw 56 threaded through the cap 55 provides an adjustable upper stop for the rack 5&3. As plate 9 descends (from the position shown in Fig. 1) carrying with it the rack guide 5i the rack 59 is held stationary by an idler gear 5? with which it is in mesh until the upper stop screw 56 contacts the upper end of rack 59 and drives it downwardly during the remainder of the stroke of the cylinder plate 9. Variations in the amount of sheet unrolled may be obtained by using racks of different lengths.

The idler gear 57 is journal'ed in the left hand bracket 35 and cooperates with a gear 59 to drive a shaft 60 through a unidirectional clutch BI. The shaft 60 is suitably journaled in left hand bracket 35 at one end and right hand bracket 36 at the other end, and projects beyond its right hand bearing to fixedly receive a gear 62. The brackets 35 and 36 have depending projections 63 and 64 which have slots at 65 that contain slides 66 to receive slidable bearing members 61 in which the feed rolls 39 and 20 are mounted. The feed rolls 39 and 40 are positioned by screws 69 and are held in contact by spring 69. Pressure between the rolls 39 and 40 may be varied by means of adjusting screws III which bear on springs 59. Rolls 39 and 40 are driven by the gear I52 fixed to shaft 60 through the intermediate gears '11 and '12, Fig. 1. Brackets and '36 are supported on rods 13 which extend from sockets 15 on the brackets downwardly to sockets 1 4 on standl.

Sheet plastic material, indicated by the letter w, is unrolled from the reel 38 by the action described above, passing over feed roll 39, Fig. 3', and back between rolls 39 and tofold loosely over a platform 16. The platform '15 is supported by brackets 16 on the rods '13. The web 10 passes between upper and lower heater plates '11, which are preferably kept at a constant temperature by electrical heating means indicated at '11, Fig. 15, or by the circulation of temperature control fluid through cored or drilled passages, not shown. The heater plates 1'1 are adjustably mounted on supports '18.

The free end of the web in normally extends beyond the plates '11 sufficiently to provide a grabbing surface for a pair of laterally disposed feedjaws '19, one near the left hand edge of the free end of web w, the other near the right hand edge. The feed jaws 19 at properly timed intervals grasp the free end of the web 20 which protrudes beyond the inner edges of the heater plates '11 and draw the sheet material over the draw plate 31. Only one of the feed'jaw devices used has been shown, since their structures are identical. Figs. 9, 10 and 11 show how, the feed jaws '19 operate. As the feed jaws approach the free end of the web w, Fig. 10, the movable jaw is in the dotted line position 89. A. flattened face 81 of the jaw '83 butts a spring mounted stop pin 82, and this action causes the jaw 80 to pivot around pin 83 to the full line position shown in Fig. 10. A toggle spring 84 serves to maintain the pivoted jaw in this position. A toothed portion 85 machined on thepivoted jaw 80 cooperates with a tooth portion 86 on a fixed jaw 8'! to firmly clamp the edge of the web 1.0.

The stop pin 82 is slidable in a plug 13E threaded into the upper heating plate '1! and is constantly urged to its extreme extension by a spring 89 which is held between the outer face of plug 83 and a fixed washer 90 on the pin 82. A head portion 91 of the stop pin 82 butts a shouldered counterbore within the plug 83 to limit the extension of pin 82. Each of the pair of feed jaws '19 are fixed to the left and right hand feed bars 93 respectively, as by screws 94, as shown in Fig. 9, said feed bars extending through pairs of guiding brackets 95 and 95, Figs. 1 and 5. Brackets 95 and 96 are mounted on spaced bracket supports 91 and 9B fixed to an auxiliary platform 99. The brackets 95, in addition to supporting the bars 93 each. carr a sliding stop pin 1113 mounted to slide in a bore in the guide bracket and held therein by tension springs 1131, Figs. 1, 4 and 5. A collar 1oz pinned to rod 139 limits the forward extension of the rod 5% through the bore in bracket 95. Only the right hand bracket 95 with its stop pin ills has been shown, but it should be clear that a similar bracket and pin assembly is located on the left to cooperate with the left hand feed jaws '13, in a manner to be later described. The feed bars 93 are reciprocated at timed intervals by an air cylinder and piston assembly through drive levers and a countershaft mechanism which will now be described.

The feed bars 93 have blocks 1133 pivotally fixed to them by pivot pins its, as shown in Figs. 1, 2 and 5, said blocks being held in slides 1&5 machined-in the upper end of feed levers 11135. The feed levers 10 6 are keyed to a cross shaft 1111 which is mounted in bearings 111B fixed to' the: auxiliary platform 99' by screws 109, Fig. 1. The; cross shaft 111'! is-driverr by a drive lever 1111- which extends through a slotted extension 111" of apiston rod 112, Fig. 5. A sliding block 113 is rotatably pinned within a slot 114' in the 'exten-' sion I 11 and is guided by slides 115. machined in the drive lever 11!). The extension 111 is sup-- ported by a guidebracket 116 which is fixed to racket ET. A stop collar 1171* limits the travel of the feed rod 112 by butting the. guide bracket 1- 13. A variety of feeds maybe obtained by vary-- ing the thickness of the stopcollar' 1.1'1'. Thepiston rod 112 is driven by a piston 1 18,,Fig. I, contained: in an ai cylinder 113 which is mounted on bracket 98.

Mechanism for extending a movable. knife blade to a cutting position under the web 11) adjacent to the draw plate 31 as shown in Figs. 1', 5 and 6, is also. driven from cross shaft 101.. Keyed to, and driven by the shaft i" 12'! are cranks 121] which carry blocks 121 rotatably fixed thereto; Figs 1, 2 and 5. The blocks 121 are adapted to receive the threaded end 122' of a knife actuating rod 1 23 which. extends below the die plate 31 through openings 1.2 lin the supporting webs 125 or the die plate supports 32., as shown in Fig. 5. The red 1 23, Figs. 5 and 6, has: a turned down portion 123 adapted to slidably receive a sleeve 1'26 pinned to a forked lever 12?. Stop collars 128 and H25 fixed to the rod portion 12-3 limit. the sliding motion of the sleeve. tZG on. slide portion 123'. The forked lever 121 is fixed on a stub shaft 13% j ournaledon one side in a casing 131' and on the other in cap 132. of the casing 131-. The shaft 135 carries a pinion 1'33; fixed thereto which cooperates with a rack' portion 1:34 of a knife support 135 A pin 13 5. 15 fixed to the outer end of stub shaft 1311 and serves as a hook on which to anchor one end of a tension spring 131. The other end of spring 1:3'1: is hooked to a screw eye 131l fi-xed to the base of the casing 131 at $39. The action of spring 131 onthe shaft 138 and the pinion 133- is such that as the rod 123 is withdrawn from the position shown in Fig. 1

the pull of the spring 13'! on the pin 136 rotates the shaft and pinion assembly counterclockwise. The forked lever 121- follows the stop me until the upper end of the knife support 135- strikes a atop-1 5E.- which is adjustabl-y mounted on the upper heating plate 1?. As the rod 123 is further retracted the portion 123' slid-es through the sleeve 1:26 until prevented from further travel by the stop i 28. Thus the knife support 535 is posi tively held in its upper position until the action of the rod 123 returning to the position shown inFig; 1 returns'the knife support 535 to its lower position through the action of the lever 12?, the pinion 1:331 and rack 134. v

A knife holder 14%! is threaded to a stud M2 loosely mounted in the knife support 135. A spring 153 provides flexibility for the knife mounting and serves to maintain it at its extended position. A knife blade 154 is mounted on the knife holder M1 as by screws 1 415, Fig. 9,

.to cooperate with an upper knife blade 14f: fixed to the clamping plate 15, Fig. 5, to cut off that portion of web w overlying the draw plate 31: when the clamping plate 1.5 descends to hold the sheet of plastic material firmly to the draw plate.

Obviously, it would be possible to control the operation of the machine described by hand. That is, an operator could push the free end of the web 10: between the heater plates, manually operate a hydraulic valve forthe reciprocation of the drive piston and the forming die, and. manually operate another valve to introduce air pressure to the feed cylinder which would advance the feed jaws and extend the lower knife blade. A faster and more efiicient method of operation is provided, however, when electrical, pneumatic and hydraulic c ontrols are introduced and properly connected to the various drive elements so that after the initial closing of an electrical switch the machine elements will perform their various functions in perfectly timed coordinationfor one cycle, if desired, or with a continuous repetition of the cycle, until the supply reel of plastic sheet material has been exhausted.

Electrical control elements or devices of well known commercial forms are put in the combination of the machine of our invention. They include a start and stop button switch, timers or timing elements, solenoids and limit switches. All have been indicated only diagrammatically to illustrate their function in the control circuit for the automatic power operation of the machine shown.

The pneumatic control devices consist of valves alternately opened and closed by the solenoids when said solenoids are electrically activated by the timing elements or limit switches; and a pair of spring loaded diaphragm valves which alternately introduce and. exhaust pressure fluid to the top and bottom ports of the die reciprocating cylinder.

The mechanism and its controls, which have been shown diagrammatically in Fig. 14, will now be described in detail. In the diagram the mechanism and controls have been shown in their rest or cycle starting position. When the male die assembly, see die 29, is in its uppermost position limit switches I41 and I48, which are fixed to the top plate 3 of the main frame, 'are held open by the cylinder plate 9. The limit switch I41 is connected by a lead I49 to one branch I50 of the supply line and by lead I5I to a line I52 which connects the open side of a switch I53 with one terminal of the timing element I54. In operation, when the start button a of the switch I53 is pressed and. held, the contact 17 of the switch, which is connected to a supply line I5fl touches contacts and (Z energizing lines I52 and I58, respectively. When pressure to button a is released, contacts b and d are held together b latch e while contacts I) and c are pushed apart by spring 1, so that, while line I58 remains energized, line I52 does not. Latch e is pivoted to release contact 1) upon pressure on stop button 9.

A timing element or device I54 has been indicated diagrammatically as consisting of an electrical device, such as a small motor, not shown, but in box it, adapted to move a contact arm 2' against a tension spring 7' when the motor is operated to bring contacts I51 and I59 together. Incorporated within the device I54, and not shown in the diagram, is timing means adapted for presetting to determine the time interval in which contacts I51 and I59 stay together. The spring 7' returns the arm to its original position at the end of the predetermined time interval. The parts indicated in device I 1 remain in the position shown even though the circuit lines I52 remains closed, until this circuit to the device is opened and again closed. This sort of time switch device is well known per se. The reset mechanism contained within the device, and not shown in the diagram, acts to reset the timing device for recycling so that when the control circuit through I52 and I55 is closed a succeeding cycle is started.

When contact I51 of device I54 is against contact I55 the following circuit is established; contact I51 to the contact (1 of switch I53, contact I59 to solenoid I60, from the latter to line I56 by lead I62, and from contact d through contact b to line I50. This results in energizing solenoid I60.

The solenoid I65 operates an air valve I63 which is connected to air pressure supply line I54 by pipe line I55, and exhausts through pipe line I55. The valve IE3 introduces or exhausts air under pressure, under the control of the solenoid I55, to a pair of air operated diaphragm valves I6? and IE8 through pipe line I69. The diaphragm valves I5? and IE8 are connected to an hydraulic pressure source through supply line Ill} and exhaust through lines III and I12. Diaphragm valve I5? is connected to the upper end of cylinder 5 by pipe line I13, while valve I68 is connected to the lower end of cylinder 6 by pipe I'M. The valves IB'I and I58 are spring loaded and so arranged that when relieved of control air, as is the condition indicated in Fig. 14, valve l5? blocks off fluid pressure from line lit and connects line I13 and the upper end of cylinder 6 to the exhaust line III, while valve I53 opens the line I'M and the lower end of cylinder 6 to the pressure supply line I'IB. These diaphragm valves for this type of function are well known.

Limit switch I48 fixed to top plate 3, and held open by plate 9, as has been described before, is connected to branch I55 of the electrical supply line by a lead I15, and to a solenoid I16 by a lead Ill. The electrical circuit to the solenoid I15 is completed by a lead H8 to branch I55 of the supply. The solenoid I controls an air valve Ill: which is connected to air pressure supply line I64 by pipe line I and exhausts through pipe line ISI. The valve I19 alternately connects the forward end of feed cylinder M9 to air pressure line I88 or to exhaust line IBI through a line I82, and introduces or exhausts pressure to the rear end of cylinder II9 through a line I83.

A third limit switch I34 supported. by bracket 91 and held closed by a lug I85 carried by lever arm I55 on shaft Ill' is connected to supply branch I55 by line I86 and to one terminal of a second timing element or device IB'I by line I88. The second terminal of timing element I8? is connected to supply line branch I55 by line I59. A contact I55 controlled by timing element I8! is connected to supply line I55 by lead I9I and connects with a contact I52 for a predetermined interval of time when the circuit to the timer I8? is closed. The timing element or device I8? is similar to timing element or device I55 in its general operation with regard to time switch control function, for its circuits. A solenoid I53 is connected to contact I92 by a lead I9 1 and to supply line 5555 by lead I55. The solenoid I93 controls an air valve I93 which is open to air under pressure through line I51. A pipe I98 connects valve I95 with an air nozzle I59 which directs an air jet in a line approximately parallel with the top of die plate 3I, and to a nozzle 2&5 which directs a jet of air approximately parallel to the front side of die 25. The nozzle 255 is flexibly connected to line I98 to provide for the travel or the die assembly.

The timing device ISI has a third contact 2i which is connected to one terminal of a switch 202 bylead 203. Asecond termin'alof the switch 202 is connected to lead "I 2. 'When switch 202 is open the machine will operate for one cycle and stop. When it is closed, as in the dotted line position in'Fig. 14, line 152 will be connected to the supply line I50, by line -I"9|, co1'i tact 1%, contact -21, line 2 93 and the switch 202. Since the circuit to timing element device 'I5'4 is completed by line 1 52 the effect will be that when switch 202 is closed the timing eleinen't device 154 will become energized when the movable ar'm i o-f timing element device I 8 returns to its rest position,-as in'-Fig. 1'4.

I So far this disclosure has concerned specific and-somewhat complicated mechanism for =making hoods or covers in the iorin of-sel fsustaining one piece hollow plastic shells from iie'xible sheet plastic material and without seams. It 'must be pointed out, however, that "the invention-does not reside in the :rn'a'chine alone. Gonceivably, the method of the invention could be carried out, and to advantage, with a minimum o'felementa'ryhand operable tools. For instance, -precut sheets of plastic material could be placed in a-heater, or oven; 'li fted'out at drawing temperature, clamped by a heated clamp plate to 'anap'e'rtured and heated draw p1ate, d'rawn to shape by'a heated die mounted to be m'oyed by 'ljland orfood press-and the'hood taken from the -di e when properly set. This method would be slew; of course, but the finished product would possess the same qualities as are possessed 'by the article produced by the automatic machine illu'strate'd. V 7 h The operation of the machine will now be described with reference to all drawings and to Fig. -14' in particular. With the machine ele ments in the position illustratedi'n Figs. 1, 2 and -14, i'f the"start button a o f switch ie His pressed, contactb touches contactscanddin the switch connecting the power source, through =line 158, to lines I52 and 1-58. Line/I52 now connects timing motor '7'L of the timing element 154 to one side I58 of the power supply, a and since the motor of box it is permanently connected to the otherside F55 of the 'power'supply-by line ="I55 the timing motor is now energized, and movesa-rm i so that contact F5? strikes contact ilfi' -anda circuit is made through-line I58',arm :2"; contacts 151 and 158 to line 1:61. The arm i will remain inthisposition for a preset-interval of time and then return tothe position of Fig. 1-4, :as has been explained earlier. This energizes solenoid I69, =valve IE6 is shifted to its intake position and control air under pressure flows through line I59 to diaphragm valves 1-67 and 168 reversing these valves so that hydraulic pressure fiuid If'rom supply Iiil now flows through -valve I61 and-pipe I13 to' the upper end of cyli- -ind'er 5', and the valve Hi8 connects the lower end of the cylinder 6 and pipe I-"Mto the exhaust -line -I-"I-2. The piston starts downwardlycarry- =ing with it the die assembly. Almost-immediately after the die'assembl-y starts its downwardtrav'el (approximately 2 inchof travel), "the actuating buttons of the limit switches I47 and 4 18 are released closing both switches. Limit switch =I4i-connects1ine I 5t and line 1 I 52 so that-it is no'longer'necessary'tohold switch -conta'c'ts c and b together andthe "start button a may be released, The other side of switch 153, that is,-that to which line I58 is connected, is locked in contact and may only be released by pressin-githe s'top button g o'ithe-switch.

When the die assembly. starts downwardly the '10 rack 50, Figs. 1, 2 and 3, drives the reed rolls 39 and '40 through the clutch -6I and gearing previously described, which action strips --f-rom the reel -38 a predetermined unit quantity of sheet plastic material. The rack 50 is -slida'ble in the guide 5| an amount limited by the adjustablestop 55 and the distance the rack 50 may slide inguide 51 determines theamount of sheet material unrolled regardless of-{the fl l'l gth of the piston stroke. The unrolled sheet plastic material remains loosely folded over ace-rm "I5 and extends between the heater plates '-'|-'I, Fig. 1.

Returning to Fig. 14, the limit switch H18 which with limit switch -I-4I is closed when the die assembly starts to descend energizes the solenoid I15 which reverses valve IlQ and-introduces air under pressure to the front end of feed cylinder I It through pipes 139 and -l-82and connects the rear end to exhaust through 'pi-pes 68-3 and =I8I. The piston H8 is driven to the opposite end of cylinder H9, as in Fig. 5, carrying-with it the rod -I-I2 and-the slotted-connection III. The lever H0 rotates the shaft *IUTI and levers I65. This results 'in the retraction "of {the pair of feed jaws 19 by sliding blocks 103 and feed bars 93, Fig. 5, and since the fre'e end of the sheet plastic material is protruding through the heater'plates TI and is firmly clamped by feed jaws I9,the sheet materialis drawn through the heater plates over the draw plate "31. free end of the web to is released when the pivoted jaw of each'of the feed jaws "T9 tFig's 10 and 11) strikes the stop rods I80, is-pivoted to its release position and is held there by the toggle action of the spring 34. stop rods mare slidably held in their normally-extended position in the guides by the springs I01 and collars I62, but are pushed part way through guides -95 by the ifeed jaw-s 19 when the feed jaws are in their retracted position,-a-s=-in'Fig. 5. Theedge of the sheet plasticinateri al hitsstop fingers 3 I ,'-Fig. 11, only one 'of-which are shown, which prevents the sheet from adhering to the toothed j'aws and being pulledbe'yond the arm p te 3|.

Rotation of the shaft 107 resultsalso in rotation of the crank 1 20 which retracts the-lewer knife actuating rod 123 from the position shown in Fig. 1 to thepo'sitien of Fig. '5. The-forked lever 121, Fig. B rOtates-under the influence 'of spring 13-1 and drives the knife support 135, through the pinion I 33 -and rack {I 35, to its cut- -'ting position, as shown in -FigsJ-5 and 6. The collar I-2-8 provides a lock a-gainst counterrotaf 'tijcnof the pinionwhen the cutting action-takes place. That when the die assembly-ap preaches the lower limit of its downwards-troke the clamping plate-I-5,-precedingthe die -'s1i-'g-htly, descends to clamp the web to the draw to '-3I, and the upper knife blade M6 carried by the clamping "plate J5 cooperates with knife -blade PM, to shear oif that, -,-portion of the web positioned ontop o'f't-he draw plate 531. The clamping plate 15 operates to clamp the we to the draw plate-tI ,bforethe {forcing action of the die takes place, by being released by the latching memb'ers I4, "Fig. "7. As -the j'd'ie assembly descends, the stop I8 pivots the latch around its-pivot I3 to releasetheclamping plate and/permit it to drop to-the cushioning 25. When the die arrives at the bottom of its stroke the-latches 14 camover the "beveled edge of the clamping plate 15 and once again sup port it. The pawl I? permits thehclding-latch I4 to pass the stop IS on the upward stroke without interference, as shown in Fig. 8.

The limit switch I84, see Figs. 1, 5 and 14, which is actuated by bracket I85 carried by lever I96, is opened when this lever is rotated by the shaft I9l, as in Fig. 5. This deenergizes the timing element I8! which automatically resets and remains in readiness for its next signal from the switch I84. 7

With the sheet plastic material now out off and clamped to the draw plate 3i by the clamp ing plate I5 the die assembly completes its downward stroke. The die enters the dr'aW aperture pushing along with it the plastic material suspended over said aperture until part of the die assembly bottoms against the draw plate I, and is held there by pressure against the piston I, as in Fig. 5. The sheet material has now been stretched tightly from the edge of the draw plate opening over the male forming die. After a preset interval of time the timing element I54 (Fig. 14) breaks the circuit between contact I59 and IE1, thus deenergizing solenoid I65. The air valve I53 returns to the position shown in Fig. 1 1 and the diaphragm valves reverse and the piston 7 starts upward and with it the die assembly. At the top or this upward stroke the cylinder plate 9 contacts the limit switches I41 and I48, opening the circuit to these switches. the circuit between power line I59 and 552, deenergizing timing element I54 which now resets automatically. Since the timing element I55 had already broken the circuit to solenoid IE8 at the bottom of the die stroke there is now no change in the solenoid I59, the valve IE3, or the diaphragm valves I51 and IE8. The piston 1 travels to the top of its stroke and is held there by hydraulic pressure.

Opening limit switch I48 opens the circuit to the solenoid valve N6, the air valve I19 reverses,

pressure is reversed in the feed cylinder II5 which causes the piston II8 to reverse its position in the cylinder and causes the feed jaws I9 to advance and grasp the web protruding from the heating plates II, the position shown in Figs. 1, 7 and 10. This action also results in a withdrawal of the lower knife holder I35 to its lower position through the retraction of the rod I23. The feed jaws I9 and the knife holder I35 through nozzles I99 and 209 in the form of a high velocity air blast, as is shown somewhat diagrammatically in. Fig. 13. The air from nozzle 280 serves to blow the formed plastic hood from the die 29 downwardly toward the draw plate 3|. At this point the jet from nozzle I99 serves to eject the article from the press up a discharge chute to a receptacle or conveying means.

The duration of this ejecting action is controlled by timing element I81 and need only be for a. very short timetwo seconds, approximately. When the preset time interval elapses the circuit is broken between contacts I99 and I92, solenoid I93 is deenergized and spring pressure returns the valve I95 to its closed position (Fig.

Opening switch Ifi'l opens 14). The circuit of the timing element I81 is still closed, but inoperative, since its circuit must be broken, through limit switch I84, before it will reset or automatically recycle to operate. Contact I95 meets contacts 25!], but if the switch 292 is open, as might be the case when setting up the machine before starting on an automatic run, there is no flow of energy between the line 253 and I52, and the machine and its controls remain in the condition shown. in Figs. 1 and 14. Th s might be termed the one cycle operation. In order to start a following cycle the start button of switch I53 must be pressed to energize line I52 and the timing element I54. However, in normal running operation the switch 292 would be closed, connecting line I52 with line 293 so that, as soon as the timing element I81 returns its contact arm 2' to rest position and its live contact I90 strikes contact 2IlI, a circuit is immediately closed to timing element I54 energizing it and automatically starting the working cycle as has been explained above.

Referring to Fig. 15, there is a power circuit i9 9 from which heating current is turned on and off in circuit 'I'l each controlled by a thermostat l9! sensitive to the temperature of its heating plate or oven parts TI to hold the oven temperature substantially constant. There is another heating circuit 29' turned on and off by a thermostat I02 sensitive to the temperature of male die part 29 to hold the temperature of this part substantially constant. There is another heating circuit I5 turned on and off by a thermostat I93 sensitive to the temperature of clamp plate I5 to hold this plate temperature substantially constant. There is another heating circuit 3|" turned on and off by a thermostat I94 sensitive to the temperature of draw plate 3I to hold this plate temperature substantially constant. Under the heatin plan indicated or an equivalent one the temperature of the sheet plastic material is made one that will draw best when it is drawn by the machine. For example the oven or heating plates 'I'I may give the sheet the right draw- 3 ing temperature and the other machine parts thereafter contacting the sheet are heated just enough to avoid heat loss until the sheet is drawn. Or the heat can be more gradually added to the sheet it being important that the sheet being drawn is carefully guarded against a marring chill and be of the right drawing softness when it is drawn.

The plan of Fig. 15 is diagrammatic only. It is sometimes useful, particularly in working plastic material, to use fluids in cored passages of tool parts to control the temperature of the plastic for working it. There is the advantage that any tendency of overheatin can be corrected by mixing hot and cold fluid to get the right tool temperature speedily. The electrical heating plan lends itself better to a simple diagram suificient for the purpose of this disclosure.

There are some particularly important things to do in providing for practicing the invention and especially important when the depth of drawing begins to or substantially exceeds one half the width of the article being made, as is indicated in the article of Fig. 12A when the depth and width are about equal. Referring to Fig. 5, the two openings one in each of the two plates I5 and 3| through which the former or male die 29 passes, should be most carefully dimensioned with respect to the thickness of the sheet plastic material, i. e. the work piece, shown in the relation of the parts in Fig. 5. Of course the male die part will be deeper when the article of Fig. 12A is made.

The dimensions should be made in all dies and especially the deep die forms, to provide a very small clearance between the sheet plastic material and the opening in the female clamping plate 3 I. For example, in forming sheet material to make successive hoods, the thickness will vary a little. Sup-pose it is between .001 and .002 of an inch. Then the openings in plates l5 and 3| should be made as close as possible to be sure to provide for such variation but otherwise omit all clearance between the material and plate 3|, as seen in Fig. 5. One fault in prior efforts to draw hoods of satisfactory finished appearance, especially the deep hoods of Fig. 12A, is in providing for too great clearance between the draw plate and die. Of course there are practical difficulties in getting extremely close dimensions. The important thing is to consider the requirements of providing for variations in sheet plastic thickness. It is available commercially with variations of a very few thousandths of an inch. When care is taken to provide the space corresponding to that seen in Fig. 5 as filled with material of the article being made, between part 26 and plate 3!, to accommodate variations of a very few thousandths of an inch in the sheet material thickness and proposals and attempts to draw fine appearing hoods whose depth is anywhere near or beyond one half their width in relative dimensions.

Another important provision in operating the method by machine work to get an economical commercial operation is this. Referring to the drawings, the flat plastic sheet is initially heated in the oven. It then moves to lie on the draw plate. This plate is heated and kept at a substantially constant temperature. The sheet is engaged between the hold down or clamping plate-l5 .and draw plate 3|. This plate 3! is also heated and. kept at a substantially constant temperature. The sheet is then engaged by the forming die 2.0. This die is also heated and kept at a, substantially constant temperature. Thus thesheet properly heated to that softness suitable for drawing is not chilled. It is neither overheated nor underheated but its drawing softness effectively provided for and guarded until the sheet is drawn to finished hood form. This is a critical thing because if the material is anywhere underheated in the area drawn there is a strain which frequently tears or wrinkles it. If the material is anywhere overheated in the area drawn there is a high liability and frequent occurrence for the sheet to be given pockmarked areas or blemishes in the finished article making it unsatisfactory for its intended use.

Another important provision is to maintain a definite and uniform pressure at the edge margin of the material, 1. e. the margin of material engaged between plates and 3|, as the material is drawn through the draw plate opening. When the material starts to be formed over the male die, it must be slightly stretched and at the same time it must be allowed to slip from underneath the hold down or clamping plate just the right amount and this can be provided for cnly by properly guarded uniform pressure on the edge of the material. The useful way to accomplish this as herein disclosed is .by the pressure due substantially to the weight alone of hold down or clamping plate 15 deposited on top of the material resting on draw plate 3|. The weight gives uniform pressure and such weight is easily made just the right weight for its hold down function. It will not vary in the operation and wear of the machine and once determined for a particular article will remain constant as long as the machine lasts. The pressure will not vary in successive operations.

It is useful to have the male forming .die heated for the reason before stated so as not to chill the material being drawn and mar its appearance. It is also desirable, however, to have this die part begin to cool the material as it is being drawn. That is, the temperature of the material can be above that of the die so that while the cooling effect or heat loss of the material is too little to interfere with the drawing, it is enough to start the material cooling toward the permanently setting temperature of the plastic material to the hood form. The material should be so set before it is removed from the forming die. The heating arrangement, i. e. a difference in the temperature of the material and the male die temperature is for the purpose of avoiding time less in the period of dwell of the material at the forming station in the operation of the machine. The machine disclosed is an expensive one and it is useful to increase its production by any means to save time in the operation of forming and then setting the sheet plastic material just that amount necessary to remove the article from the male die.

From what has been stated one will understand the importance of a close temperature control in the operations of making the articles not only to guard their quality but to use the tools and the machine most efficiently. To disclose the plan with reference to a diagram, one indicated as suitable to electric heating means is shown in the drawings. Another suitable means not shown is by coring the tools for the passage of fluid to control the temperature. This way would have the advantage that the fluid could be quickly changed in temperature by mixing cool and hot fluid for passage through the tool metal to hold the temperature down on any tendency to overheat. The diagram of the drawings shown is only a diagram to indicate the plan for close temperature control of machine parts. It will be sufiicient to disclose the nature and principles of temperature control for efficient operation and one which is highly desirable to quality of the articles to be made. The equivalency between electrical and hydraulic means for holding the right temperature of the machine tools will be apparent without diagramming the hydraulic means in the drawing. a

The invention having now been disclosed, the claims are:

l. A machine to make hoods from sheet plastic material comprising in combination, a horizontally arranged drawplate having anopening with an edge corresponding to a, base line of a hood, a roll support adapted to hold a roll of plastic sheet material, a web support for the material, power driven means adapted to intermittently draw portions of material off its roll and put it on the web support in loose web condition, an open ended oven in position for the web to pass through toward said draw plate, web feeding means including power driving means to feed the forward end of the web intermittently to draw one part into the oven and another heated part from the oven across the draw plate to cover its opening, web cutting means to shear ofi the portion of web covering the draw plate opening clam-ping means to press the margin of the heated out part around the draw plate opening, power tool reciprocating means mounted above the draw plate opening, a drawing tool, in the shape of a core corresponding to a hood cavity, such tool carried by said reciprocating means, the aforesaid elements being operable under power for repeated cycles of operation, to draw a heated sheet portion from the oven, cut it off from the continuous web clamp it over the draw plate opening, move the drawing tool against the plastic material and draw the latter to hood form while the material at the edges of the opening is held in flat pressed condition by the clamping means, and air blast means adapted to blow aside the cutoff drawn portion clear of the drawing tool after the latter has operated and the clamping means has been released.

2. A machine to make hoods from sheet plastic material comprising in combination, a horizontally arranged draw plate having an opening with an edge corresponding to a base line of a hood, a roll support adapted to hold a roll of plastic sheet material, a web support for the material, power driven means adapted to intermittently draw portions of material off its roll and put it on the web support in loose web condition, an open ended oven in position for the Web to pass through toward said draw plate, web feeding means including power driving means to feed the forward end of the web intermittently to draw one part into the oven and another heated part from the oven across the draw plate to cover its opening, web cutting means to sever the heated part when said part is in position across the draw plate opening, clamping means to press the margin of the heated part around the draw plate opening, power tool reciprocating means mounted above the draw plate opening, a drawing tool, in the shape Of a core corresponding to a hood cavity, such tool carried by said reciprocating means, the aforesaid elements being operable under power for repeated cycles of operation, to draw a heated sheet portion from the oven, sever it from the continuous Web clamp this blank over the draw plate opening, move the drawing tool against the plastic material and draw the latter to hood form while the material at the edges of the opening is held fiat by the clamping means to permit controlled slipping, air blast means to blow the cut off drawn portion to one side of the drawing tool after the latter operates and such cut on" portion is unclamped, and power operated timing means for controlling the sequence in the power operation of said elements whereby the machine is adapted for fully automatic operation to make hoods one after another, except in relation to replacing exhausted spools of the sheet plastic material.

3. A machine for shaping articles from predetermined lengths of thermoplastic sheet material comprising, the combination of, a web supply support adapted to hold a we supply of plastic sheet material, a power driven web feed assembly adapted to feed predetermined lengths of the web from the web supply, a web support positioned beneath the level of the web supply and the feed asse; y a horizontally disposed support for the web as it passes from the feed assembly, heating means forming a heating zone positioned adjacent said Web support in horizontal alignment therewith whereby successive predetermined lengths of the web may be pulled horizontally from the web support to said heating zone for heating with the leading end of the web at the edge of the heating zone opposite said web support, a forming die assembly positioned adjacent the heating zone at the side thereof opposite said web support and adapted to receive the predetermined lengths of the web from the heating zone, said forming die assembly including a horizontally arranged plate having an opening with an edge corresponding to a base line on an article being formed, web-cutting means to shear on? the portion of the web covering said opening, clamping means to press the margin of the heated cutoff part around said opening, and means to shape the web into said opening to form articles, power operated web-pulling mechanism comprising web clamping means to clamp the leading edge of the Web and elongated means supporting said web clamping means, and mechanism to operate said web-pulling means through a cyclic operation whereby said web clamping means is caused to engage and clamp the leading end of the web at the edge of said heating zone and is then moved through the zone of said forming die assembly a distance equal to said predetermined length of the web, whereby a heated length of the web is drawn from the heating zone into the forming die assembly and another length of the web is drawn into the heating zone.

4. A machine for shaping articles from predetermined lengths of thermoplastic sheet material comprising, the combination of, a web supply support adapted to hold a web supply of plastic sheet material, a power driven web feed assembly adapted to feed predetermined lengths of the web from the web supply, a web support positioned beneath the level of the Web supply and the feed assembly and presenting a horizontally disposed support for the web as it passes from the feed assembly, heating means forming a heating zone positioned adjacent said Web support in horizontal alignment therewith whereby successive predetermined lengths of the web may be pulled horizontall from the Web support to said heating zone for heating with the leading end of the web at the edge of the heating zone opposite said web support, a forming die assembly positioned adjacent the heating zone at the side thereof opposite said web support and adapted to receive the predetermined lengths of the web from the heating zone, power operated web-pulling mechanism comprising we'b clamping means to clamp the leading edge of the web and elongated means supporting said web clamping means, and mechanism to operate said web-pulling means through a cyclic operation whereby said web clamping means is caused to engage and clamp the leading end of the web at the edge of said heating zone and is then moved through the zone of said forming die assembly a distance equal to said predetermined length of the Web whereby a heated length of the web is drawn from the heating zone into the forming die assembly and another length of the web is drawn into the heating zone.

5. A machine as described in claim 4 wherein said web-pulling mechanism comprises a plurality of individually operating units each of which includes one of said elongated means in the form of a bar and one of said Web-clamping means in the form of a top law rigidly fixed to its bar and g 1 7 swingable bottom jaw spring-urged into engagement with its top jaw, and stationary abutment means which is adapted to engage and swing the lower jaws away from the upper jaws at the end of each web-pulling operation.

6. Apparatus as described in claim 5 wherein each of said lower jaws is provided with a, spring which is adapted to retain the jaw in either of its extreme positions wherein it either clamps against its upper jaw or is positioned spaced therefrom, means positioned adjacent said heating zone to move each of the lower jaws into clamping relationship, and wherein said mechanism to operate the web-pulling means comprises a rocking lever construction pivoted at its lower end on a horizontal axis beneath said bars and mechanically interrelated at its upper end to said 18 bars, and hydraulic means to SWing said rocking lever construction.

CHARLES EDGAR MAYNARD. LEWIS I-I. GUSTAFSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,521,387 September 5, 1950 CHARLES EDGAR MAYNARD ET' AL.

It is hereby certifiedthat error appears in the printed specification of the above numbered patent requiring correction as follows:

, Column 7, line 69, after the Word circuit insert through; column 12, line 25, for circuit read fimuits; and that the said Letters-Patent should be read as corrected above, so that the same may conform to theirecord of the case in the Patent Oflice. Signed and sealed this 2nd day of January, A. D. 1951.

THOMAS F. MURPHY,

Assistant Oovnmz'ssz'oner of Patents. 

